Field of the Invention
The present invention relates to a method of manufacturing an optical fiber and an apparatus of manufacturing the same.
Description of Related Art
In manufacturing of an optical fiber, a method in which an optical fiber is drawn toward a vertically lower direction from an optical fiber preform along a linear path is generally adopted.
In the manufacturing method, there is a restriction on the height of the entire system as a factor affecting productivity. The reason that the height of the system is a main factor which restricts productivity is because it is necessary to ensure a distance for sufficiently cooling a bare optical fiber which is obtained by drawing the optical fiber preform.
When a new facility including a building is built, the restriction can be relaxed; however, an enormous cost is required for building a new facility, and when it is required that productivity is further improved in the future, it is necessary that a new facility will be built at higher cost.
As a method of relaxing the restriction, a method is included in which a direction changer including a fluid bearing is used.
The fluid bearing is for holding a target to be in a noncontact state using the pressure of a fluid such as air, and in the direction changer including the fluid bearing, it is possible to perform direction change with respect to the bare optical fiber without being in contact with the bare optical fiber (a bare fiber).
By using the direction changer, it is possible to change the direction of the bare optical fiber which is subjected to the fiber drawing from the optical fiber preform along the first path to conform to a second path (for example, refer to Japanese Patent No. 5571958 and Japanese Unexamined Patent Application, First Publication No. S62-003037).
In Japanese Patent No. 5571958, a manufacturing method is disclosed in which an apparatus for direction change including a groove into which an optical fiber is introduced and an opening formed in the groove is used. In this method, gas introduced to the apparatus is blown out from the opening through one inflow port, and the direction of the optical fiber is changed in a state where the optical fiber is floated due to the pressure of the gas.
A direction changer disclosed in Japanese Unexamined Patent Application, First Publication No. S62-003037 includes a guide groove which guides a bare optical fiber, and a blowout port for gas which is formed on a lower surface and both side surfaces of the guide groove (refer to Examples, and FIGS. 3A to 4). In the manufacturing method using the direction changer, the direction of the optical fiber is changed in a state where the optical fiber is floated due to the pressure of the gas blown out from four blowout ports.
However, in the manufacturing method disclosed in Japanese Patent No. 5571958 and Japanese Unexamined Patent Application, First Publication No. S62-003037, positioning accuracy of at least a μm order is required at the time of disposing the apparatus for direction change (for example, refer to Claim 8 in Japanese Patent No. 5571958).
The reason that an accurate position adjustment is required for disposing the apparatus is because the bare optical fiber is damaged when the bare optical fiber is in contact with an inner surface of the groove of the apparatus, and the strength of the bare optical fiber decreases.
For this reason, it is necessary that the bare optical fiber is floated by maintaining a narrow gap of approximately a few dozen μm between the bare optical fiber and the inner surface of the groove. In addition, it is necessary to accurately adjust the position of a central axis (a path line) before and after the direction change. However, since the gap is small, it is very difficult to adjust the position.
The present invention has been made in consideration of the above-described circumstances and an object of the present invention is to provide a method of manufacturing an optical fiber and an apparatus of manufacturing an optical fiber capable of relaxing a requirement for accuracy in a disposing position of an apparatus for direction change.